From an outsiders perspective, which is what it seems you were looking for by posting here, this is an unhealthy relationship that will probably end badly. I hope that isn't the case, and it obviously isn't what you want to hear, but that's the reality. What is going to be different this time? Is she open to counseling? Will it make a difference? You've listed several negatives about getting involved with her again, are you sure you're willing to deal with them, and with unforeseen difficulties as well?

Be careful, and try to let your head make the decision instead of your heart. It's hard, I know, when those feelings are there.